As apparatuses and a method for displaying volumetric images, a stereoscopic image display device of Patent Literature 1 and an optical imaging device and optical imaging method of Patent Literature 2 have been known so far. The technique described in Patent Literature 1 is one that forms volumetric images as real images on a surface on an opposite side of a display device by arranging a large number of dihedral corner reflectors in a grid-like pattern, and making light having reflected off one surface of each of the dihedral corner reflectors reflect off a surface orthogonal to each of these dihedral corner reflectors.
The optical imaging device of Patent Literature 2 was one in which a first and second light-controlling panel each having a large number of belt-shaped, planar light-reflective portions are arranged such that the planar light-reflective portions in the first light-controlling panel are aligned orthogonal to the planar light-reflective portions in the second light-controlling panel, and with which stereoscopic images arranged on either a front surface side or a back surface side of the optical imaging device become formed on the other side as real images, the planar light-reflective portions in the first light-controlling panel being orthogonal to the front and back surfaces of the first light-controlling panel, the planar light-reflective portions in the second light-controlling panel being orthogonal to the front and back surfaces of the second light-controlling panel.
In Patent Literature 3, there is disclosed a stereoscopic image display device with which stereoscopic images become formed in the air by planarly arranging a large number of corner cubes (cubic corner bodies) used as retroreflective bodies and made of a transparent body (glass, plastic), making a top of each of the corner cubes a flood light hole by notching the top, and forming half-mirrors at light-receiving holes.